Pallet for sintering machines



Nov. 20, 1962 v. F. KOONTZ PALLET FOR SINTERING MACHINES eat 2 3Sheets-Sh INVENTOR.

VICTOR F. KOONTZ Filed Sept. 21, 1961 Fig.2.

his ATTORNEYS 1962 v. F. KOONTZ 3,064,961

PALLET FOR SINTERING MACHINES Filed Sept. 21, 1961 3 Sheets-Sheet 3INVENTOR. VICTOR F. KOONTZ BY M his ATTORNEYS United States Patent3,064,96l PALLET FOR SINTERENG MA-QHENELl Victor F. Koontz, Coraopolis,Pa, assignor to Dravo Corporation, Pittsburgh, Pa, a corporation ofPennsylvania Filed Sept. 21, rear, Ser. No. 139,724 13 Claims. (Cl.Zed-21) This invention relates to apparatus for sintering of ore orother materials or the heat-hardening of pellets, and is for a palletfor use in such apparatus.

It is well-known in the art to sinter ore or heat-harden pellets and tomake cement clinker by loading loose material or preformed pellets intothe trays or pallets of sintering machines and the material so loaded isconveyed through various heating or burning and cooling zones. Themachines, often referred to as Dwight-Lloyd types of machines, generallyhave a horizontal track between the rails of which are located a seriesof wind-boxes con nected either to a suction fan or blower, dependingupon Whether there is a down draft of combustion gases or an up draft ofcooling air. A series of separate pallets are placed in succession ontoone end of this trackway with the pallets in abutting relation so thatas each pallet is added to said end, all of the pallets are pushed alongtoward the opposite end, moving in succession over the series ofwind-boxes. At the discharge end of the horizontal track, each pallet inturn is tipped to dump its charge, and lowered onto a return track tothen move back to the loading end of the machine, and again elevated tothe beginning of the line on the horizontal track.

At the entering end of the horizontal track the pallets are loaded witha charge and they may pass under one or a succession of hoods locatedover the tracks, and to which hot air, flame, burning gases orcombinations thereof may be supplied, or in which suction is maintainedto move gases upwardly through the pallets and the charge which theycontain.

Usually the charge in the pallets contains fuel or oxidizable materialsso that as air or flames are drawn from the hood above to a wind-boxbelow, combustion or an exothermic reaction takes place in some areas oftravel, while at another location cold air may be blown upwardly throughthe pallets, or the charge may be heated to incandescence from flamesbeing drawn downwardly through it. At any rate the charge, and thepallets, the charge-supporting bottoms of which comprise grate bars,become highly heated. They are sometimes cooled by cooling air beingforced upwardly through the charge, and are further cooled as they areemptied and move through the return part of their cycle.

As a result of this drastic heating and cooling, the pallets, which areof heavy metal, become warped and weakened. As they become increasinglywarped, it becomes more difiicult to maintain the seals between them andthe wind-boxes. The replacement of pallets is therefore a costly factorin the operation of sintering apparatus of this type.

One major reason for the warping of the pallets arises from the factthat it is difficult in a heavy structure of this kind to relievethermal stresses lengthwise of the pallets. Another cause of warpingarises from the unequal vertical heating or thermal gradient in avertical direction, the grates immediately under the charge being heatedmore drastically than the structure below this level.

The present invention has for its principal object to provide a palletof improved construction, which will be longer lived, and is lesssubject to destructive warpage.

A further object of this invention is to provide a pallet in which thegrate-supporting bars are separate from the main structural members ofthe pallet, and the main structural members are at a level where theheat is less intense.

A further object of the invention is to provide a pallet in which thegrate-supporting bars are in short lengths or sections, each free toexpand and contract without transmitting any stresses to the mainstructural members.

A further object of the invention is to provide a pallet in which allstructural sections of substantial vertical depth are fabricated fromparts which are designed to sulfer minimum warpage due to a temperaturegradient from top to bottom, and are composite structures, whilecontinuous elements extending the length of the pallet are of shallowvertical depth, so that they are little afiected by any temperaturegradient from top to bottom.

A further object of the invention is to provide a pallet which isfabricated from metal plates and bars with only selected parts beingcast, as distinguished from integral castings heretofore generallyprovided.

These and other objects and advantages are secured by the invention aswill be more fully apparent to those skilled in the art from thefollowing description, in conjunction with the accompanying drawings. Inthe drawmgs:

FIG. 1 is a perspective view in transverse section showing a portion ofone end of a pallet embodying my invention;

FIG. 2 is a top plan view of a portion of the pallet shown in PEG. 1with the end section removed;

FIG. 3 is a longitudinal section in the plane of line IIIIII of FIG. 2;

FIG. 4 is a side elevation of one section of the grate bar-supportingassembly removed from the pallet;

FIG. 5 is an end view of the assembly shown in FIG. 4 for a grate barsupport intermediate to the sides of the pallet;

FIG. 6 is a similar view of a section of the grate bar support for thesides of the pallet;

FIG. 7 is a fragmentary transverse section in the plane of line VII-VIIof FIG. 2;

FIG. 8 is a transverse fragmentary section of the end assembly of thepallet, the view being in approximately the plane of line VlII-VIII ofFIG. 1;

FIG. 9 shows a modified grate-supporting bar section, the view being atransverse vertical section through the bar and its complementary fillerplate; and

FIG. 10 is a view similar to FIG. 8 showing in longitudinal section thepallet assembly utilizing the modification of FIG. 9, line X-X on FIG. 9indicating the plane of the section.

The general construction of the pallet may be best seen in FIG. 1, inwhich 2 designates an end casting which is separate from the rest of thepallet, and which is bolted thereto, as best seen in FIG. 8. It is thisportion of the casting that carries the usual seals as indicated, forexample, by the channel 3 at the bottom of the casting 2, and it is thisend member which carries the rollers (not shown) that support the palleton the tracks along which it moves.

According to the present invention there is an end plate member 4 ateach end of the pallet which butts against the end casting 2, and whichis fabricated from two metal plates in tace-to-face relation. The endplate member 4 at one end of the pallet is connected to a correspondingplate at the other end of the pallet by a plurality of heavy bars 5.These rods or bars are preferably of solid section, although they neednot be, and they are preferably circular in section, although this isnot necessary. They are, however, preferably of relatively small sectionin a vertical direction. These bars 5 are spaced one from another andprovide the rigid structure connecting the two ends of the pallet. Theends of the bars are welded to the plates 4 against which they abut,

As shown in FIGS. 2 and 8, each end plate 4 is faced against the endcasting 2, and is bolted thereto. The ends of the continuous bars 5 arecut away or fiattened at two sides as indicated at 5a in FIG. 2 wherethis is necessary to give clearance for the entry of the bolts throughthe holes in the end plates.

At intervals along the bars 5 between the end plates are transverseplates 6 best shown in FIG. 2, these having openings therethroughthrough which the rods 5 pass.

The plates 6 have welded or otherwise aflixed to each face thereof pairsof vertical cleats 7 of generally rightangle section with one legsecured to the plate 6- and one leg or flange projecting outwardly fromthe plane of the plate 6, the cleats of a pair being spaced from eachother as indicated at d. The cleats are provided with a vertical seriesof holes 9 therethrough in that flange of the cleat which is normal tothe plane of the plate 6. These pairs of cleats are located centrallybetween each two rods 5, and the corresponding pairs of cleats are inlongitudinal alignment lengthwise of the pallet. At the outermost end ofeach plate 6 there is a single such cleat 10, and there is a confrontingvertical strip 11 welded to the end of the plate 6 and spaced from themember 19 the space being designated 12 in FIG. 2.

On the face of the end plate 4 against which the ends of the rods 5abut, and to which the rods are Welded, there are matching pairs ofsimilar cleats also designated 7 with spaces 8 therebetween, and at theends there are single cleats 1t) and vertical strips 11 like those onthe plates 6. There is a space 12 between the cleats 1t) and 11 on theseend plates.

Lengthwise of the pallet the spaces 8 are all in alignment as are thecleats themselves, and the spaces 12 are all in alignment.

Referring particularly to FIG. 4, there is shown a grate bar-supportingmember designated generally as 15, which may be fabricated from metalplate, and one form of which has a top strip 16 that is welded to thetop edge of a vertical plate 17 forming a generally T-shaped sectionwith the strip 16 projecting each side of the plane of the plate 17.These members 15 have depending leg portions 18 in which arehorizontally-elongated bolt holes 19, and between the legs 18 the plateis cut away so that the member 15 as viewed in FIG. 4 is somewhat of anarch shape. These members 15, as best shown in FIG. 1, have the end legsthereof fitted into the spaces 8 between the pairs of cleats 7, andbolts passing through the holes 9 and through the horizontally-elongatedbolt holes 19 serve to connect the members 15 with the cross plates andhold them at the proper vertical elevation. Along each side of thepallet there is a similar row of grate-supporting members designatedgenerally as 15a which are in all respects similar to the members 15,except that the top flange or strip 16a extends inwardly only toward thecenter line of the pallet, and does not project outwardly to each sideof the plane of the main plate 17. In other words, while the tops of themembers 15 are T-shaped in section, the tops of the members 15a are ofan inverted L section. The members 15a are held in place between thecleats and 11 by means of bolts, the same as the members are held inplace.

The individual grate bars are shown in FIG. 1 and they are of thegeneral construction commonly used in sintering pallets. They comprise abar 20 which is generally flat on top, and which is deeper at each endthan it is at the center, and each end is bifurcated as indicated at 21,so as to slidably lit the flanges 16 or 16a, as the case may be, of thegrate bar-supporting members 15 or 15a, the bars thus resting on theflanges of the members 15 and 15a. The top flange-forming strip 16 onmember 15 is wide enough so as to accommodate the ends of two sets ofbars in end-to-end relation. The outside members 15a of course have toengage only the ends of one set of bars, and for this reason the strips16a are narrower and project only inwardly from the plane of plate 15a.

As these pallets travel along in the sintering machine they move from aposition over one wind-box to a position over another. If the members 15and 15a were not otherwise complemented with end plates to close thearchway between depending legs 18, air or gases could travel freelythrough the pallets and defeat the purpose of the separate wind-boxes ofthe machine. Therefore, each grate-supporting member, as shown in FIG.4, has a complementary tiller plate 22 having end portions 22a which arereceived in the spaces between the cleats the same as are the ends ofthe grate-supporting members themselves, and the plates 22 have widecentral portions 22b which substantially close the archway between thelegs 18 of the grate-supporting members. The members 22 have elongatedbolt holes 23 therethrough similar to the bolt holes 19, and in verticalalignment therewith, and the lowermost bolt passing through a hole 9 inany one of the cleats passes through an opening 23 in one of thesecomplementary arch-closing or filler pieces.

It will thus be seen that the pallet has main load-bearing members ortie bars 5 of short vertical height or depth, and spaced well below thetops of the grate bars, and the only direct heat-conductng path from thegratesupporting bar members 15 and 15a to the rods 5 is through therelatively thin transverse plates 6. Because of the rods or bars 5 beingof solid section, there is a good heat-conducting path from top tobottom thereof, and because of the rods being of relatively smalldiameter, particularly in a vertical direction, there is aninsignificant heat gradient between the top and bottom surfaces of therods, wherefore they tend to expand and contract quite uniformly. Inpallets as heretofore generally constructed, the grate bars have beencarried on wide, flanged, deep sections, the top flanges of which areclose to the heat of the charge in the pallets, and the lower flanges ofwhich are several inches removed from the intense heat of the charge, sothat there was a considerable temperature gradient vertically, and theunequal stresses developed a permanent deformation that increased as thepallet was used, to a point where replacement was necessary.

In the present invention the grate bars are carried on the short membersor sections 15 and 15a, which in turn transmit the weight of the load tothe main loadcarrying members 5 through the cleats and transverse plates6. Moreover, the grate-supporting sections are spaced and mounted so asto isolate expansion and contraction effects from the bars or rods 5which carry the main bending stresses and are relatively littlesubjected to differential heating and cooling because of their shape andmass.

The grate-supporting members 15 and 15a are each of relatively shortlength so that the thermal expansion in any one of them is relativelysmall, and there is not the cumulative effect of expansion in theseshort sections independently supported, which there is in a continuouslong section as employed in pallets as heretofore constructed. Theelongated bolt holes 19 in the legs 18 of the grate bar-carryingsections permit independent longitudinal expansion and contraction ofeach individual support, and because of the arch form of the members 15there is no continuous deep web to expand unevenly. The complementaryplates 22 can expand and contract independently of the members 15 intowhich they are fitted, but for all practical purposes in sealing oif theshort-circuiting of the air flow, they function the same as continuousdeep Webs of the structural sections of conventional pallets.

The end castings 2 are attached to the end plates 4 by bolts 25 passingthrough the end plate assemblies 4 and through the vertical web of theend casting as shown in FIG. 8. As previously noted, the flattening ofthe ends of the rods 5 and 5a is to afford access to the heads of thesebolts which are designated 25. The end casting may have a separateupwardly-extending end wall-forming piece 26 bolted thereto. The palletis the same at each end, so that the drawings illustrate the structureat only one end. The basic structure comprising the end members 4, thebars 5 and the cleats, is symmetrical about its medial plane so that,should it be desired, the grate-supporting bars and filter plates may beremoved, the structure turned over, and the parts so removed thenreplaced on the second side, thus providing a reversible pallet.

In the modification shown in FIGS. 9 and 10, the structure of the palletis the same as that disclosed in the previous figures, with theexception that the cleats for attaching the grate bar-supportingsections to the members 6 are carried on the grate bar-supportingsections instead of on the plates 6. Also, the cleats for holding thefiler members are on these members instead of on the transversesupporting members 6.

In these two figures, only so much of the entire structure as isnecessary to describe the modification is shown. The gratebar-supporting section is designated generally as 30 and is providedwith a top flange 31. The grate bar-supporting sections would have theflanges 31 arranged either as shown in FIG. 5 or FIG. 6, depending onwhether the sections were used along the outsides of the pallet orintermediate to the sides. 33 indicates the separate filler piececorresponding to the member 22 of the structure previously described.The transverse supporting member of the pallet structure, correspondingto the member 6 is designated 34.

According to the modifications here shown, the ends of grate bar section30 are provided with laterally-extending cleats or pads 35 through whichare holes 36. These pads face against the member 34. The holes 36register with holes of the same diameter in the cross members 34. Asleeve 37 passes through the registering holes. A bolt 38 passes throughthe sleeve, and a nut 39 on each bolt is tightened to secure the partstogether. The sleeve 37 is slightly longer than the combined thicknessof the several metal sections through which it passes, so that when thenut is tightened on the bolt it will be limited by contact with the endsof the sleeve, and cannot bind against the faces of the pads 35. Thegrate bar-supporting sections are thus supported in the proper position,but in a manner which provides sufficient clearance to allow each gratebar-supporting section to expand and contract independently of theothers. In like manner the extension 40 at the bottom of the plate 33 isprovided with similar pads 41 that project laterally from the ends ofthe plate. These pads are provided with holes that register with holesin the cross member 34, and there is a sleeve 41 corresponding to thesleeve 37 and similar bolts 42 with nuts 43 are provided so as to securethe separate plates 33 in position on the cross members, but allow alsofor the expansion and contraction.

In each of the structures as above pointed out, main load-carryingmembers are at a level Well below the level of the grates and arepositioned between the grate-supporting bars and are not a contiguouspart of the gratesupporting bars. Their section is such that there islittle temperature gradient between the top surface and the bottomsurface of these rods or bars, and there is no good heat-conducting pathfrom the grate bars to the rods. The tie rods 5 are of substantiallysmaller section in a horizontal direction than the distance between thesectional grate-supporting bar assemblies, so that there is adequatespace for the flow of air or gases through the spaces between adjacentgrate bar-supporting assemblies. By making the grate-supporting bars inshort lengths, each can expand and contract a slight distance withoutafiecting the overa.l length of the grate-supporting assembly, andconditions tending to produce warpage are thereby substantiallyalleviated.

It will also be noted that the vertical webs of the gratesupporting barsare cut away or notched inwardly at the ends so that the tops mayoverhang the transverse supporting plates or end plates with only aslight gap between the confronting ends of the grate-supporting bars orbetween the endmost bars and the ends of the pallet. The pallet as thusconstructed has a plurality of parallel gratesupporting bar assemblies,each comprised of sections in confronting end-to-end relation withslight spaces between section ends suflicient to allow each section toexpand lengthwise independently of the other sections, and each sectionis supported in the structure in a manner that such expansion introducesno stress into the main framework of the pallet.

While I have shown and described certain embodiments of my invention, itwill be understood that this is by way of illustration, and that variouschanges and modifications in details of construction may be made withinthe contemplation of my invention and under the scope of the followingclaims.

I claim:

1. A pallet for sintering machines and the like comprising a pair ofspaced parallel end members, a series of parallel spaced gratebar-supporting assemblies extending transversely to the end membersbetween the two end members, parallel tie bars connecting the endmembers, the tie bars being staggered between the grate barsupportingassemblies, each grate bar-supporting assembly comprising a series ofseparate sections in end-to-end relation with confronting ends spacedsufliciently to permit independent lengthwise expansion thereof,transverse plates on the tie bars extending between the ends of thesections of the grate bar-supporting sections, and means on saidsections and the transverse plates through which aligned sections areconnected with each other for independent expansion and contraction, thetops of said grate bar-supporting sections extending to a level abovethe tops of the tie bars.

2. A pallet for sintering machines and the like comprising a pair ofspaced parallel end members, a series of parallel spaced gratebar-supporting assemblies extending transversely to the end membersbetween the two end members, parallel tie bars connecting the endmembers, the tie bars being staggered between the grate bar-supportingassemblies, each grate bar-supporting assembly comprising a series ofseparate sections in. end-to-end relation with confronting ends spacedsufliciently to permit independent lengthwise expansion thereof,transverse plates on the tie bars extending between the ends of thesections of the grate bar-supporting sections, and means on the sectionsand the transverse plates through which aligned sections are connectedwith each other for independent expansion and contraction, the tops ofsaid sections extending to a level above the tops of the tie bars, thetops of said sections of the grate-supporting bar assemblies beingflanged, and grate bars in side-by-side relation spanning the spacebetween each pair of grate barsupporting assemblies, the grate barshaving end portions slidably fitted over the flanges of said sections.

3. A pallet for sintering machines and the like comprising a pair ofspaced parallel end members, a series of parallel tie bars connectingthe end members, a series of parallel spaced grate bar-supportingassemblies extending transversely to the end members between the two endmembers, the tie bars being staggered between the grater bar-supportingassemblies, each grate bar-supporting assembly comprising a series ofseparate sections in slightly spaced end-to-end relation, transverseplates on the tie bars extending between the ends of the sections of thegrate bar-supporting assemblies, and means on the sections and thetransverse plates through which aligned sections of each assembly areconnected with each other for independent expansion and contraction, thetops of said sections extending to a level above the tops of the tiebars, the tops of the grate-supporting bar assembly sections beingflanged, the ends of the sections overhanging the transverse plates.

4. A pallet for sintering machines and the like comprising a pair ofspaced parallel end members, a series of parallel tie bars connectingthe end members, a series of parallel spaced grate bar-supportingassemblies extending transversely to the end members between the two endmembers, the tie bars being staggered between the grate bar-supportingassemblies, each grate bar-supporting assembly comprising a series ofseparate sections in slightly spaced end-to-end relation, transverseplates on the tie bars extending between the ends of the sections of thegrate bar-supporting assemblies, means on the scetions and thetransverse plates through which aligned connections of each assembly areconnected with each other for independent expansion and contraction, thetops of said sections extending to a level above the tops of the tiebars, said means on the sections and transverse plates through whichaligned sections are connected comprising cleats on the transverseplates which overlap the ends of the grate sections, the sections of thegrate barsupporting assemblies having horizontally-elongated holesthrough the ends thereof, and fasteners passing through the cleats andsaid horizontally-elongated holes.

5. A pallet for sintering machines and the like comprising a pair ofspaced parallel end members, a series of paralled tie bars connectingthe end members, a series of parallel spaced grate bar-supportingassemblies extending transversely to the end members between the two endmembers, the tie bars being staggered between the grate bar-supportingassemblies, each grate bar-supporting assembly comprising a series ofseparate sections in slightly spaced end-to-end relation,'transverseplates on the tie bars extending between the ends of the sections of thegrate bar-supporting assemblies, means on the sections and thetransverse plates through which aligned sections are connected with eachother for independent expansion and contraction, the tops of saidsections extending to a level above the tops of the tie bars, the topsof said extensions having confronting flanges, and grate bars withbifurcated ends engaging the flanges of sections of adjacent gratebar-supporting assemblies and spanning the space crosswise of the palletfrom the grate bar-supporting section of one assembly to thecorresponding sections of an adjacent assembly at a level spaced abovethe tie bars.

6. A pallet for sintering machines and the like as defined in claim 1wherein the ends of those sections of the grate bar-supportingassemblies that terminate at the end members are attached to said endmembers in the same manner that the sections of the assemblies areattached to said transverse plates.

7. A pallet for sintering machines and the like as defined in claim 1wherein the ends of those sections of the grate bar-supportingassemblies that terminate at the end members are attached to said endmembers in the same manner that the sections of the assemblies areattached to said transverse plates, the tie bars passing through saidtransverse plates.

8. A pallet for sintering machines and the like as defined in claim 1wherein the sections of the grate bar-supporting assemblies are of archform with each end thereof comprising a downwardly-extending leg, and aseparate filler plate closing the space under the arch between the legs,and means for securing the filler plates in place.

9. A pallet for sintering machines and the like comprising a pair ofspaced parallel end members, a series of parallel tie bars connectingthe end members, a series of parallel spaced grate bar-supportingassemblies extending transversely to the end members between the two endmembers, the tie bars being staggered between the grate bar-supportingassemblies, each grate bar-supporting assembly comprising a series ofseparate sections in slightly spaced end-to-end relation, transverseplates on the tie bars extending between the ends of the sections of thegrate bar-supporting assemblies, means on the sections and thetransverse plates through which aligned sections o are connected to eachother for independent expansion and contraction, the tops of saidsections extending to a level above the tops of the tie bars, saidlast-named means comprising cleats on the transverse plates, thesections of the grate-bar-supporting assemblies havinghorizontallyelongated holes therethrough, and fasteners passing throughthe cleats and said elongated holes, said sections of arch form whichdepending ends and an open central area, and a complementary fillerplate filling said open central area of each section, the filler plateshaving ends which extend under the ends of the section which itcomplements, the ends of said filler plates being attached to the cleatson the transverse plates in the same manner that the sections areattached to the cleats on said transverse plates.

10. A pallet for sintering machines and the like as defined in claim 1wherein the tie bars are of substantially smaller vertical section thanthe maximum depth of the sections of the grate bar-supporting assembliesand are substantially narrower in a horizontal direction than the spacebetween adjacent grate bar-supporting assemblies whereby there is freespace for the flow of air vertically through the spaces between thegrate bar-supporting assemblies around said tie bars.

11. A pallet for sintering machines and the like as defined in claim 1wherein the tie bars are solid round rods of a diameter substantiallyless than the distance between adjacent grate bar-supporting assemblies.

12. A pallet for sintering and like machines comprising spaced endmembers, a plurality of spaced parallel tie bars connecting the endmembers, a plurality of parallel grate bar-supporting structuresextending the length of the pallet spaced from the parallel tire bars,the gratesupporting structures comprising a plurality of separatesections in end-to-end relation with flanges at the tops thereof abovethe level of the spaced tie bars, means on the tie bars and end platesfor supporting the ends of the said separate sections and holding therespective section of each such grate bar-supporting structure inconfronting end-to-end relation with the other sections of the samestructure and the ends of one section spaced from the ends of anadjoining section a distance suificient to permit each to extendlengthwise independently of the other, and a series of grate bars havingbifurcated ends engaging the flanges of the next-adjacent parallelsections at a level above the tops of the tie bars.

13. A pallet for sintering and like machines comprising spaced endmembers, a plurality of spaced parallel tie bars connecting the endmembers, a plurality of parallel grate bar-supporting structuresextending the length of the pallet spaced from the parallel tie bars,the grate-supporting structures comprising a plurality of separatesections in end-to end relation with flanges with the tops thereof abovethe level of the spaced tie bars, means on the tie bars and end platesfor supporting the ends of the said separate sections and holding therespective section of each such grate bar-supporting structure inconfronting end-to-end relation with the other sections of the samestructure with clearance spaces between sec tions sufiicient to enableeach section to expand under heat independently of theconfrontingsections, a series of grate bars having bifurcated endsengaging the flanges of the next-adjacent parallel sections at a levelabove the tops of the tie bars, each such separate section of the gratebar-supporting structure being of arch form having leg portions at eachend to which said means on the tie bars and end plates are attached, anda separate plate filling the opening through the arch of each section.

References Cited in the file of this patent UNITED STATES PATENTS2,245,136 Shallock June 10, 1941 UNITED STATES PATENT OFFICE CERTIFICATEOF CORRECTION Patent No S O64 96I November 20 1962 Victor E. Koontz Itis hereby certified that error appears in the above numbered patentrequiring correction and that the said Letters Patent should read ascorrected below.

Column 5, line 18 for "fil er read filler column 6 llne 63,, for"grater" read grate *3 column 8 line 7 after "sections" insert beingline 8 for wnich" read wi th 5 Signed and sealed this 14th day of May1963 (SEAL) Attest:

ERNEST w. SWIDER DAVID LADD Attesting Officer Commissioner of Patents

